Friction gearing



Aug. 12, 1930.

J. H. ROBERTSON FRICTION GEARING Filed July 7. 1928 3 Sheets-Sheet 1 Aug. 12, 1930. ROBERTSON 1,772,593

FRICTION GEARING Filed July 7, 192a s SheeQs-Sheet 2 5 4 c /2 .2 777/ 1 d d J m k 2 5 h e 2 a A? 52 F g- 1930. w J. H. ROBERTSON 1,772,593

FRICTION GEARING Filed July '7. 1928 3 Sheets-Sheet 3 Patented Aug. 12, 1930 JOHN EOGG ROBERTSON, OF LONDON, ENGLAND FRICTION GEARING Application filed July 7,1928, Serial No. 291.122, and in Great Britain April 10, 1928.

This invention relates to friction gearing of the variable type, in which'the ratio of transmission can be varied between two-extreme values by displacement of one of the 35, members relatively to theother, and more particularly to that type, of friction gearing in which one extreme value of the transmission ratio is obtained by direct engagement of the two members in the manner of a friclotion clutch, the variations from this extreme value towards the other extreme being obtained by displacing one member laterally so that the frictional engagement takes place by contact at points of limited areas ofwhich the respective radial distances from the axes of the two members are unequal.

The invention has for its object to provide an improved continuously variable friction gearing of the above type, in which the axes of tially parallel, thedisplaceable member bethe two members remain always substaning supported by a radius arm controlled by a spring or the like and adapted to swing around an axis to one side of and parallel .to the axes of the two members, the movemerit of the radius arm causing the axis of the displaceable member to travel along a circular arc approximating to a radius of the other member.

Theinvention has also for an object to provide improved means for controlling the position of the laterally displaceable member, preferably in an automatic manner and in accordance with the speed and torque of the two members, the laterally displaceable member being caused to swing around the axis of its radius armby relative axial displacement of one or both of the two members,

the latter having conical engaging surfaces 1S0, that the axial advance of one member to wards the other tends to bring them into the l coaxial position whereas the contrary movement allows the laterally dlsplaceable mem- Figure/7, but representing the position of ber to move towards the eccentric position h The relative axial displacement ofthe two members may be produced automatically or to Figures 1 and 2, but representing a second member of which the axial displace- 'ment is controlled by the operator.

The invention has the further object of providing an arrangement of parts whereby control of the position of the displaceable member is obtained automatically by causing the torque acting through that member to react upon the spring-controlled radius arm so as to increase or decrease the lateral displacement of the displaceable member. In conjunction therewith, the invention comprises the provision of means for the axial displacement of the other member, the ad- Vance or withdrawal of which further reacts upon the spring-controlled radius arm, said axial displacement being determined by a governor or equivalent device in accordance with the speed of said'other member.

The invention is hereafter described with reference to the accompanying drawings, which show a' form of construction suitable for a light motor vehicle as illustrating one embddiment of the'invention. In these drawmgs,

Figure 1 is a longitudinal sectional view of the drivin and driven members, the latter being disp aced laterally upwards from the axis of the driving member.

Figure 2 is an end view, as seen from the left of Figure 1. r

Figure 3 is a detail seen in section on the line 33 of Figure 1.

Figures 4 and 5 are views corresponding the positions of the parts when the two members become coaxial.

Figure 6 is a diagramfexplaining the automatic control of the displaceable member by the torque acting upon it.

Figure 7; illustrates the arrangement of a manual control of the variable-- gearing, together-with a reversing geanf i Figure-Sis a partial viewcorresponding parts when, the manual controlwithdraws the drivenme'mber from contact with the driving member. I

I Figure -9 isia'view of the manual control lever on a larger-scale,

Figure 10 is aconventional representation of an automobile fitted with a variable fric- .tional gearing according to thepresent mvention.

Referring to Figures 1 to 5, there is mount- "ed upon the engine shaft a and in place of the usual flywheel, a driving member in the form of a hollow cylindrical box I) having a cover 0 including a coned end disc 0 this cover being slidable axially upon the exterior "of the box 6, but normally held back towards the latter by springs 41 enclosed in thimbles stud of each pair is fitted with a roller 6.

Inside the box there is mounted a rotatable cage in the form of a cylindrical ring f, which is supported at one edge by a ball thrust race f w Ie the opposite edge is notched or cut 7 away to form cams f at positions correspond- I ing to the spacing of the slots 19 and rollerfitted studs e; the rollers e engage with the cam surfaces f so that rotation of the cage ring f in one direction will cause'the covers to travel axially forward from the box b, against the action of the retaining springs d the rotation of the cage being produced by "a governor which tends to advance the cover in proportion as the speed of rotation inas creases. The governor comprises weighted rials employed for the re contacting faces being of ifierent friction' coeflicients, as described inmy concurrent levers g pivoted at 9 upon the back of the box I) and having toothed segments g gearing with part circular racks f on theinterior. of the cage f, as described in my concurrent patent a plication Serial No. 291,121.

The s aft h transmitting the drive from the friction gearing has its forward end con nected by a universal joint h to the driven member ofthe friction gear, rovision being made for axial movement, fer example'by employing a plunging universal joint of the known 'nd. J

The driven member of the friction gear is mounted upon a shaft 2' supported in suitable bearings 11 at the free end of a radius arm 1,

the rear end of this shaft 2' carrying the uni versal joint h, and the forward end of'this shaft icarrying the driven member itself, which is constructed inthe form of a wheel is having an annular friction face-k. coned to the same angle as the disc face 0 of the slidable cover 0 upon the driving member. The

driven member mayinclude (as shown) an intermediate disc k carrying on one side the friction face It and engaging -on its other side with a second friction face k',.the mate tive pairs of patent application Serial No; 291,123;

by a nut n.

- takes erted on the slida The radius arm j may be of length somewhat greater than the radius of the driving and driven members, as shown in Figure 2, so that it swings around a center 7' to one Side of the two members, the shaft '1: of the driven meinber being thus movable laterally of the driving member alonga part-circular path from a position near one edge of the latter (Figures 1 and 2) to a position coaxial therewith (Figures 4 and 5). For convenience, the pathof the laterall displaceable driven member is may be ma e to follow a curve (indicated by chain lines in Figures 2 and 5) approximatin to a vertical radius of the driving member, t e pivot 7' of the radius arm being provided by a pin carried by a bracket 1 upon one of the side members of the vehicle frame and the driven member rising gradually as it is displaced from the coaxial position (shown in Figure 5) into the successive positions of indirect drive until it reaches the extreme position shown in Figures 1 and 2. I j

The radius arm 7' is controlled byia telescopic spring link m, which acts between a ball and socket abutment m upon the opposite side member Z of the vehicle frame and an upward extension 7' of the radius arm, the spring m enclosed in'the telescopic link actin compression so as to tend to raise the in radius arm j and thereby to displace the driven member is away from itscoaxial' osition (Figures 4 and 5) in line with the riving shaft 0; and member 1),, towards the indirect drive position shown 1n Figures 1 and 2. .The radius arm 7' is preferably a T-shapc,

having a lower extension 7' on the side opposite extension 1*, to which lQWGIflXtGnSlOIl there is connected for example by means of a .ball joint M, an abutment such as a, thrust rod nl ingbeside'or ap roximately parallel to the riven shaft h an more or less in line with the driving shaft 0, which abutment enables the shaft 2' to resist the pressure actingcbetween the driving and driven members. The other end ofthe thrust rod n may be provided, as shown on the left of Fi ure 1, with a' spring buffer device n and a all-jointed member n which takesthe thrust, the initial compression of the spring being adjustable With the. partsat rest or with the engine runnin at' low speed, no effective contact ace between the coned driving and .t e driven wheel, is but as soon as the engine is brought up to a predetermined speed by .depressing an acceleratorpedal or theposition of Figures land 2. ,When the engagement takes 'place, the axial force exe c by the governor cover 0 so as to bring the the ann at face]: of the driven member in c increase, the governor device arranged to device is conveyed to the friction surfaces, motion being transmitted to the driven member 70 as soon as this force producesa sufiicient torque to overcome the resistance to move ment; the two members then revolve in the same direction but eccentrically to one another and at different speeds, the gear reduction being proportional to the respective radii from the point (or limited area) of contact.

If the speed of the engine continues to pushes the slid able cover a further forward, which causes "the driven member is to move towards the coaxial position, the radius arm jbeing rotated in opposition to its controlling spring link m; the driven member k thus brought more and more nearly concentric with the driving member, with a resultant. gradual raising of the gear ratio, until the two members finally attain the coaxial position shown in Figures 4 and 5, when the friction faces make contact for the whole of their circumferences, giving a direct drive from theengine to the propeller shaft. Theefiect of the buffer device 11* is to limit the pressure acting between the driving cone and driven disc, and further to reduce this pressure automatically as the gear is raised, the movement of the wheel is to wards the coaxial position allowing the spring buffer to relax as the wheel travels down the cone, the radius'arm j being slidable along its pivot 9' as'hereafter described.

If the speed of the engine decreases for any reason, the governor device will allow the coned disc 0 to recede' from the driven member, the spring-controlled radius arm j then displacing the driven member is laterally up- 'wards to maintain the frictional engagement but at a lower gear ratio. I The spring control by the link we may be exert-a maximum effect when n the lowest gear position and to have a diminished effect in the higher gear positipns, by so disposingthe spring link m' that it forms a kind of toggle device in combination with the extension 7' of the radius arm, the leverage ofthe spring link decreasing as the driven member approaches the direct drive position, Figure 5. v

In addition to the automatic variation of gear according to the an additional or complementary variation according to the resistance to motion,\because the force transmitted to the driven member A: at the point of frictional engagement in the positions of indirect drive reacts upon the radius arm j, producing a couple which tends to turn the arm about its pivot.

Figure 6 represents the action of the principal forces involved, the diagram being arranged as viewed from the driving side, that is, looking in the opposite direction to Figures 2 and 5;

engine speed, there is O is the center of the driven member, in its laterally displaced position;

A is the center of the area of contact begtiveen the driven member and the driving so; I

B represents the arm;

F is the tangential driving force acting upon the driven member at the point A, and exerting a torque around the point 0 (shift i) which torque is balanced by an equal and opposite couple due to the resistance to movement of the driven shaft h. couple or torque reaction can be represented by two forces F and F each equal to F and acting at half the radial distance OA.

pivot, (7' of the radius i F F this resultant being equal to F and acting parallel to the latter but through the center 0. Resolving this force F into its components, one f along the radius arm 7' in the direction OB, the other f at right angles thereto, the component f produces a couple around the point 0 tending to swing the radius arm 7' in a counter-clockwise direction, as viewed in Figure 6, and to maintain the driven member in the position of upward lateral displacement. The component f 1s equal to the resultant F force F) multiplied by the cosine of the angle (a) between F and f being therefore a maximum when the driven member is at its extreme indirect drive position. This component due to the torque reaction'assists the spring control by the link m, both forces ten ding to keep the gear in the lowest r at1o. Consequently the variation of gear is n this case controlled automatically partly by the spring (that is, equal to the This opposing link m and partly by the relation between the .two opposing factors of engine-speed and resistance-torque, and for the same engine-speed the gear-ratio will be higher on the level or when running downhill than when .climbially towards or away fromthe driving disc,

so as to provide a higher or alower ratio according to circumstances, by the operation of a hand lever p connected to the rear end of the thrust rod 12; the pivot j of the radius arm is for this reason provided by a spindle (see Figure shaft on the radius arm j being slidable along that spindle as well as being adapted to swing upon the spindle as a center. When the manual control is operated, as shown in Figure 8, to withdraw the driven memben k whol away from the driving disc, no dr1ving engagement can take place, even when the disc is advanced to its full extent by the governor mechanism. At intermediate positions of the manual control, the drivingen 7) lying parallel to the engine tained in its position after adjustment, by

means of a toothed quadrant g engaged by a tooth or pawl p uponthe lever, the latter having atrigger p or like device for releasing the pawl p when it is desired to alter the position of adjustment. The same operatmg'lever is also used to obtain a free position inde endent lv of the accelerator or like control, or example, when it is required to obtain a reverse drive by means of the supplementary gear box 1' (Figure 7), while the lever 19 maintains the friction gear in the freeposition, as in Figure 8; the depression of a catch 1 upon the hand lever p'engages a rocking piece 1' mounted on the same pivot g as the lever, so that by returning the and-lever 1) towards its normal position, tension is applied toa spring link 1- which engages the reverse gear as soon as the teeth or jaws ofthe engaging members come into line. After reversing, the hand-lever p must be operated again to obtain the free position before the reverse gear can be disengaged.

With this arrangement, the invention provides a continuously variable friction gearing which is automatic in operation under normal running conditions, but can be regulated independentlyby hand at the will of the driver, and in addition includes reversing mechanism controlled entirely by the ee H same manual regulating means.

Such an arrangement is particularly well I suited for light automobiles; I have illustrated in Figure 10 a vehicle comprising a frame 1, wheels 8, engine t and steering gear u, the drive from the shaft It being trans mitted through the reverse gear box r to the back axle 'v in any suitable way, for example by bevel gearing as well known in the art.

- It will be understood that the invention T is not limited to the'particular embodiment described, but that it may be applied to variable gearing for other classes of machinery, especially where an automatic Variation is required within limits which can beadjusted b hand or otherwise according to the condltions of operation.

What I claim is i 1.. A variable friction gearing, comprising driving and driven members, said members having their axesof rotation substantially parallel, said driving member including a conical disc adapted to contact with said driven member, means for advancin said. conical disc axially into contact with said driven member, a radius arm supporting said driven member, said radius arm permitting lateral displacement of said driven member relatively to said driving member, the pressure between said conical disc and said driven member tending to swing said radius arm in oneiangular direction to bring said driven member coaxial with said conical disc, and

' spring operated means tending to swing said ber and the force exerted by said means tending to swing said radius arm in the opposite angular direction.

2. A variable frictiongearing, comprising driving and driven members, said members having their axes of rotation substantially parallel,'said driving member including a conical disc adapted. to contact with said driven member, means for advancing said conical disc axially into contact with said driven member, a radius arm supporting said driven member, said radius arm permitting lateral displacement of said driven member relatively to said driving member, speed controlled means for exerting pressure between said conical disc and said driven member, said pressure tending to swing said radius arm in one angular direction to bring said driven membercoaxial with said conical disc, and

means tending to swing said radius arm in the opposite angular direction to bring said driven member to an eccentric position.

3. A variable friction gearing, comprising driving and driven members, said members havingtheir axes of rotation substantially parallel, said driving member includin a conical disc, means governed by the spee of said driving member for advancing said conical disc axially into contact with said driven member, aradius arm supporting said driven member, said radius arm permitting lateral displacement of said driven member relatively to said driving member, the pressure between said conical disc and said driven member tending to swing said radius arm in one angular direction, andthe fulcrum of said radius arm being so disposed relatively to said members that the reaction of the torque acting between said members at the area of contact tends to swing said radius arm in the opposite angular direction.

4. A variable friction gearing, comprising having their axes of rotation substantially parallel, saiddriving member includin a conical disc, means governed by the spee of said driving member for advancing said conical disc axially into contact with said driven a driving member,

place. said conical drlvlng member, a dIlVGIl crum of said radius arm being so disposed relatively to said members that the reaction of the torque acting between said members at the area of contact tends to swing said radius arm in the opposite angular-direction to bring said driven member to an eccentric position, the angular position ofsaid radius arm and the amount of lateral displacement permitted to the driven member varying with the rela- 1 tion between the pressure acting between said speed-governed conical disc and said driven member and the torque transmitted to said driven member at the area of contact.

5. A variable friction gearing, comprising a driving member, an axially displaceable conical disc forming part of saiddriving member, governor mechanism tending to dis place said conical disc axially according to the speed of said driving member, a driven member having its axis of rotation substantially parallel to that of said driving member, a radius arm supporting said driven member, said radius arm permitting lateral displacement of said driven member relatively to said driving member, said conical disc advancing into contact with said driven member when displaced axially b increased speed of said driving member, t e pressure between said members when in contact tending to swing said radius arm in an angular direction to bring said members towards coaxial position, and means tending to swing said radius arm in the opposite angular direction.

6. A variable friction gearing, comprising an axially displaceable conical disc forming part of said driving member, governor mechanism tending to disdisc axially according to the speed of said member having'its axis of rotationv substantially parallel to that of said driving membar, a radius arm supporting said driven said radius arm permitting lateral displacement of said driven member relatively to said driving member, said conical disc advancing into contactwith said driven member when displaced axially by increased speed of said driving member, the pressure between said members when in contact tend-- ing to swing said radius arm in an angular direction to bring said members towards coaxial position, and the fulcrum of said radius arm being so disposed relatively to said members that the reaction of the torque acting between said members at the area of con tact tends 'to swing said radius arm in the opposite angular direction.

axis of rotation porting said driven member,

ment of said driven member mentary means for 7. A variable friction gearing, comprising a driving member, a conicalpdisc forming part of said driving member, means for disp acing said' conical disc axially in a resilient manner, a driven member having its substantially parallel to that member, a radius arm supsaid radius arm permitting lateral displacement of said driven member relatively to said driving member, a spring link controlling the angular position of said radius arm, and a thrust member connected to thrust member acting approximately parallel to the axes of said driving and driven members to controlthe position of saiddriven member, said conical disc advancing into resilient contact with said driven member when displaced axially, and the pressure between said conical disc and said driven member tending to swing said radius arm in an anguof said driving lar direction against the control of said spring radius arm supporting said driven member,

lateral displacerelatively to said driving member, resilient means for controlling the angular position of saidradius arm to move said driven member to an eccentric position, spring controlled means for advancing said axiall displaceable disc into contact with said d iiven member, so as to bringsaid driven member into a position cosaid radius arm permitting said radius arm, said axial with said driving member and supple:

displacing said driven member axially in the direction of'the advance of said axially displaceable disc,

(gearing, compris- 9. A variable friction ing a driving member, sai driving member including an axially displaceable disc, governor mechanism, tending to displace said disc axially according to the speed of vsaid drivin member,a driven member having its axis 0 rotation of said driving member, said driven member including a frictionring' adapted to contact with said displaceable disc at variable relative eccentricity, a radius arm'sup'porting said'drivenmember, a fulcrum for said radius arm, said radius armpermitting lateral ing to swing said radius arm in the opposite angularf directicm, and the fulcrum ofjsaid radi m. be n 9 d sease elat e F9 substantially parallel to that.

displacement of said fdrivenmember' relamember,

26 said one member,

- said displaceable disc,

alternative gear drives and means for select- 80 selecting means laterally of the 45' eccentricity,

5o thr t member including a spring bufi 60 so as no lon er said members that the reaction of the torque acting between said members tends to swing said radius arm in the angular direction to increase said relative" eccentricity.

, 10. A variable friction gearing, comprising' driving and'driven members, said members having their axes of rotation substantially parallel, automatic means for displacing one of said members laterally of the other I said other member including an axially displaceable disc, automatic speed controlled means for dis lacing said disc axially in relation to sai one member, and supplementary manually operated means for 1 displacing said one member axially in relation to said displaceable disc.

11. A variable friction gearing, comprising driving and dr1ven'members,sa1d members having their axes of rotation substantialg0 1y parallel, automatic means for displacing one of said members laterally of the other member, said other member including an axially displaceable disc, automatic means for displacing said disc axially in relation to and means for withdrawing said one member axially out of contact with in combination with alternative gear drives, said being operable only while said one member is withdrawn from contact with said displaceable disc.

12. In an automobile, the combination of variable friction gearing comprising driving ing one of said and driven members, said members having their axes of rotation substantially parallel, means for displacing one of said members other of said members, automatic means for exerting pressure between said members, said automatic means being governed by the speed of rotation of said driving member, and the contact between said members taking place at radial distances varying with the amount of their relative a displaceable thrust member acting approximately parallel -.to the axes of said driving and driven members to. support said driven member against the pressure be- ..tween said members when in contact, said er evice, alternatiye gear drives included in the transmission from said driven member,

means for selecting (one of said alternative gear drives, and trol', said control regulating the action of said a manually operated conthrust memberand including supplementary control means for operating said selecting means, said selecting means being operable only while sai thrust member is displaced to maintain said driving and driven mem rs in contact with one another. 13. In a variable friction gearing, comprising driving and driven members with conical surfaces adapted for frictionaldrivin contion substantially parallel, and a radius arm supporting said driven member to permit its lateral displacement to a position eccentric of said driving member, the combination of an axially displaceable disc forming the conical surface of said driving member, and automatic means governed by the speed of its rotation for displacing said disc axially upon said driving member and in relation to said driven member, the pressure acting between said disc and said driven member when in contact tending to swing said radius arm in one angular direction to bring said driven member coaxial with said conical disc, and the reaction of the torque transmitted by said driven member acting to swing said radius arm in the opposite angular direction to bring said driven member to an eccentric position.

14. In a variable friction gearing, compris- 1ng drivlng and driven members with conical surfaces adapted for frictional driving consaid members having their axes of rotathe reaction of the torque transmitted by said driven member acting to swing'said radius arm in the opposite angular direction to bring said driven member to an eccentric position, and supplementary manually operated means for dis lacing said driven member axially away rom said conical disc to allow of further angular movement of said radius arm to bring said driven member to a position of greater eccentricity than would normally be the case.

In testimony whereof I' hereunto aflix my signature.

JOHN HOGG ROBERTSON.

as tact, said members having their axes o rota- 4 

